1. Field of the Invention
The present invention relates to methods for producing ceramic compacts, such as ceramic substrates, and particularly to a method for producing a ceramic compact, such as a ceramic substrate, obtained through a constraint firing step in which an unfired body is attached to a constraining layer and then fired such that the transverse shrinkage of the unfired body is prevented.
2. Description of the Related Art
Ceramic electronic components, particularly ceramic substrates, must have high two dimensional accuracy. The transverse shrinkage of the ceramic electronic components fired in firing steps and the variations in shrinkage seriously affect product quality.
There are some methods in which ceramic compacts are fired so as to prevent shrinking in firing steps. For example, the following method has been disclosed: a firing method (hereinafter referred to as constraint firing) in which a ceramic compact 51 is fired so as to substantially prevent transverse shrinkage by covering both principal surfaces of the ceramic compact 51 with constraining layers 52a and 52b primarily including a sintering resistant material, such as alumina as shown in FIG. 4, such that the sintering-resistant material is substantially sintered at the firing temperature of the ceramic compact 51 (see, for example, Japanese Unexamined Patent Application Publication No. 4-243978).
In the conventional firing method, the constraining layers, which are not sintered and remain on the ceramic compact 51, must be physically or mechanically removed by wet blasting or another suitable process after the firing step is completed. This causes a problem in that the production steps are complicated.
Since recent electronic components are compact and thus require thin ceramic substrates and elements, there is a problem in that if the conventional firing method is used to produce a multilayer ceramic substrate, the substrate may crack during a step of removing constraining layers.